Manufacture method for photovoltaic module

ABSTRACT

The invention permits a plurality of strips of resin adhesive film having a desired width and unwound from a single feeding reel to be simultaneously pasted on a solar cell. For this purpose, the invention comprises the steps of: unwinding a resin adhesive film sheet from a reel on which the resin adhesive film sheet is wound; splitting the unwound resin adhesive film into two or more film strips in correspondence to lengths of wiring material to bond; pasting the strips of resin adhesive film on an electrode of the solar cell; and placing the individual lengths of wiring material on the electrode of the solar cell having the plural strips of resin adhesive film pasted thereon and thermally setting the resin adhesive film by heating so as to fix together the electrode of the solar cell and the wiring material.

The priority application Number JP2009-70469 upon which this patentapplication is based is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a manufacture method for photovoltaicmodule.

2. Description of the Prior Art

A photovoltaic module has a construction wherein a plurality of solarcells are connected in series and/or in parallel by means of wiringmembers electrically connected to electrodes on front and back sidesthereof. In the manufacture of the photovoltaic module, the conventionalpractice is to use solder for connecting the electrodes of the solarcells with the wiring members. The solder is widely used because of itsexcellent connection reliability including conductivity, bondingstrength and the like.

From an environmental standpoint and the like, on the other hand, thesolar cells also employ a wiring connection method not relying on thesolder. There is known a method, for example, which uses a conductiveadhesive film to interconnect the solar cells and the wiring material.Such a method is disclosed in, for example, United States PatentPublication No. 2009/0288697A1.

To connect the wiring material using the conductive adhesive film, theconductive adhesive film first need be pasted on a collector electrodeof the solar cell. The conductive adhesive film is normally wound on areel. A conductive adhesive sheet is unwound from the reel and anunwound portion of the sheet is pressure bonded to the solar cell bymeans of a film pasting device. Thus, the conductive adhesive film ispasted on the collector electrodes of the solar cells.

FIG. 12 is schematic perspective view showing an arrangement of the filmpasting device. As shown in FIG. 12, the device comprises a conductiveadhesive film feeding reel 200 having a conductive adhesive film sheet50 wound thereon, and a carrier film take-up reel 201. The conductiveadhesive film sheet 50 unwound from the feeding reel 200 is advanced tothe carrier film take-up reel 201 by means of guide rolls 202, 202 via apasting stage to past the film sheet on a solar cell 1. A conductiveadhesive film 5 is pasted on a predetermined portion of the solar cell1.

Before reaching the pasting stage, the conductive adhesive film sheet 50is half-cut by a cutter 203 such that only an adhesive layer thereof iscut to a length in which the film sheet is pasted on the solar cell 1.

At the pasting stage, the conductive adhesive film sheet is pressedagainst the solar cell 1 at a predetermined pressure. Subsequently, theconductive adhesive film 5 is peeled off a carrier sheet and pasted onthe solar cell 1. The carrier sheet is advanced from the guide roll 202to the carrier film take-up reel 201 so as to be wound thereon. Anapparatus has been contemplated which employs such film pasting devicesfor pasting the films on plural places in the apparatus. Such a methodis disclosed in, for example, JP2004-78229(A).

A single apparatus having a mechanism for pasting the conductiveadhesive films on upper and lower sides of a substrate negates the needfor turning over the substrate of the solar cell requiring the films tobe pasted on the upper and lower sides thereof. This makes it possibleto reduce tact time.

However, the above-described method has the following problems becauseit requires as many conductive adhesive film feeding reels as thepasting stages of the pasting devices.

Firstly, the increase of the pasting positions leads to the increase ofthe feeding reels and thence, cost increase. Furthermore, a problemexists that the number of pasting lines is limited by the number offeeding reels.

Another problem is that the choices of width of the conductive adhesivefilm depend upon vendor's performance and hence, the width of theconductive adhesive film cannot be decreased from a given width. Thatis, the conductive adhesive film having too small a width cannot bewound on the reel. As it now stands, the conductive adhesive film musthave a width of about 1.0 mm or more to be wound on the reel.

By the way, it is desired to reduce the width of the wiring materialbecause the wiring material bonded to a light-incident side of the solarcell blocks the incident light. In a case where a wiring material havinga width of 0.5 mm is used, for example, the conventional practice is tobond the wiring material with a conductive adhesive film having a widthof 1.0 mm. As thermally set, the conductive adhesive film becomes tintedso that the light is shielded by the tinted portion of the film. Eventhough the 0.5 mm-wide wiring material is used, the light is shielded bythe 1.0 mm-wide conductive adhesive film, which makes it impossible toincrease light use efficiency.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a method which permits aplurality of strips of conductive adhesive film having a desired widthand wound on a single feeding reel to be simultaneously pasted on thesolar cell so as to reduce costs and unwanted light shielding.

In accordance with the invention, a manufacture method for photovoltaicmodule, in which a wiring material is electrically connected to anelectrode of a solar cell by using a resin adhesive film, comprises thesteps of: unwinding the resin adhesive film from a reel on which theresin adhesive film is wound; splitting the unwound resin adhesive filminto two or more strips in correspondence to lengths of wiring materialto bond; pasting the strips of resin adhesive film on the electrode ofthe solar cell; and placing the individual lengths of wiring material onthe electrode of the solar cell having the two or more strips of resinadhesive film pasted thereon and thermally setting the resin adhesivefilm by heating so as to fix together the electrode of the solar celland the wiring material.

The above arrangement permits the resin adhesive film fed by a singlefeeding reel to be split into plural strips of adhesive film anddelivered simultaneously and hence, the apparatus cost can be reduced.Furthermore, the light shielding by the resin adhesive film can beeliminated by making the width of the conductive adhesive film equal toor slightly smaller than that of the wiring material.

In accordance with the invention, the manufacture method forphotovoltaic module employs: a first reel on which a resin adhesive filmcorresponding to an electrode on a front side of the solar cell iswound; and a second reel on which a resin adhesive film corresponding toan electrode on a back side of the solar cell is wound, and furthercomprises the steps of: unwinding the resin adhesive films from thefirst and second reels, respectively; and splitting each of the unwoundresin adhesive films into two or more strips in correspondence to thelengths of wiring material.

The above arrangement permits the resin adhesive films to besimultaneously pasted on the front and back sides of the solar cellwithout turning over the solar cell.

It is preferred to provide a length adjustment mechanism somewherebetween a place of the splitting step and a place of the pasting step inorder to ensure that all the strips of resin adhesive film move the samedistance from a position of the reel to pasting positions on the solarcell.

All the strips of resin adhesive film are guided over the same distancewhereby the resin adhesive film can get used up without being wasted.

An arrangement may be made such that the resin adhesive film comprisesan adhesive layer overlaid on a base material and a take-up device fortaking up the base material is disposed downstream of the pastingpositions on the solar cell.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing a photovoltaic module whereinelectrodes of solar cells and a wiring material are interconnected usinga conductive adhesive film;

FIG. 2 is a sectional view schematically showing the photovoltaic modulemanufactured according to the invention;

FIG. 3 is a schematic sectional view showing the conductive adhesivefilm employed by the invention;

FIG. 4 is a plan view showing a solar cell having the conductiveadhesive film pasted thereon according to the invention;

FIG. 5 is a plan view showing a principal part of the photovoltaicmodule manufactured according to the invention;

FIG. 6 is a schematic sectional view showing the principal part of thephotovoltaic module manufactured according to the invention;

FIG. 7 is a plan view showing steps of feeding and pasting theconductive adhesive film according to a manufacture method of theinvention;

FIG. 8 is a side view showing the steps of feeding and pasting theconductive adhesive film according to the manufacture method of theinvention;

FIG. 9 is a side view showing the steps of feeding and pasting theconductive adhesive film according to the manufacture method of theinvention;

FIG. 10 is a schematic diagram showing individual steps of themanufacture method for photovoltaic module of the invention wherein theelectrodes of the solar cells and the wiring material are interconnectedusing the conductive adhesive film;

FIG. 11 is a schematic diagram showing the steps of the manufacturemethod for photovoltaic module of the invention wherein the electrodesof the solar cells and the wiring material are interconnected using theconductive adhesive film; and

FIG. 12 is a schematic perspective view showing an arrangement of aconventional film pasting device.

The foregoing and other objects, features, aspects and advantages of thepresent invention will become more apparent from the following detaileddescription of the present invention when reviewed in conjunction withthe accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A preferred embodiment of the invention will be described in detail withreference to the accompanying drawings. In the drawings the same orsimilar reference numerals are used to refer to the same or similarcomponents which are explained only once to avoid repetition.

FIG. 1 is a plan view schematically showing a photovoltaic modulemanufactured according to the invention. FIG. 2 is a sectional viewschematically showing the photovoltaic module fabricated according tothe invention. FIG. 3 is a schematic sectional view showing a conductiveadhesive film employed by the invention. FIG. 4 is a plan view showing asolar cell having the conductive adhesive film pasted thereon accordingto the invention. FIG. 5 is a plan view showing a principal part of thephotovoltaic module manufactured according to the invention. FIG. 6 is aschematic sectional view showing the principal part of the photovoltaicmodule manufactured according to the invention.

The embodiment of the invention employs a conductive adhesive film, forexample, as a resin adhesive film. As illustrated by the schematicsectional view of FIG. 3, a conductive adhesive film 5 comprises atleast a resin adhesive component 5 b and conductive particles 5 adispersed therein. The resin adhesive component 5 b having theconductive particles 5 a dispersed therein is overlaid on a base film 5c made of polyimide or the like. The resin adhesive component 5 bcomprises a composition containing a thermosetting resin. Examples ofthe usable thermosetting resins include epoxy resins, phenoxy resins,acrylic resins, polyimide resins, polyamide resins, polycarbonate resinsand the like. These thermosetting resins may be used alone or incombination of two or more types. It is preferred to use one or morethermosetting resins selected from the group consisting of epoxy resins,phenoxy resins and acrylic resins.

Examples of usable conductive particles 5 a include metal particles suchas gold particles, silver particles, copper particles and nickelparticles; and conductive particles, such as gold plated particles,copper plated particles and nickel plated particles, which compriseconductive or insulative core particles coated with a conductive layersuch as a metal layer.

According to the embodiment, the conductive adhesive film 5 having awidth of 1.7 mm is wound on a feeding reel 51.

First, a photovoltaic module 10 manufactured according to the inventionwill be described with reference to FIG. 1 and FIG. 2.

As shown in FIG. 1 and FIG. 2, the photovoltaic module 10 comprises aplurality of plate-like solar cells 1. This solar cell 1 comprises, forexample, a crystalline semiconductor made of monocrystalline silicon orpolycrystalline silicon having a thickness on the order of 0.15 mm andis generally shaped like a square 104 mm or 125 mm on a side. However,the invention is not limited to this and may employ any other solarcell.

An n-type region and a p-type region, for example, are formed in thesolar cell 1 while an interfacial area between the n-type region and thep-type region defines a junction for forming an electric field forcarrier separation. The n-region and p-region can be formed by usingsemiconductors for use in solar cell singly or in combination, thesemiconductors including crystalline semiconductors such asmonocrystalline silicon semiconductors and polycrystalline siliconsemiconductors, compound semiconductors such as GaAs and InP, and thinfilm semiconductors such as thin films Si and CuInSe having an amorphousstate or microcrystalline state. For example, the embodiment may employa solar cell which includes an intrinsic amorphous silicon layerinterposed between monocrystalline silicon and amorphous silicon layershaving the opposite conductivities so as to reduce defects in interfacestherebetween and to achieve improved heterojunction interfacecharacteristic.

As shown in FIG. 4 and FIG. 5, the solar cell 1 is formed with collectorelectrodes 115, 119 in predetermined regions of front and back sidesthereof. The collector electrode 115, 119 is an electrode for collectingphotogenerated carriers generated by a photoelectric conversion portionin the solar cell 1. The collector electrode 115, 119 includes, forexample, a plurality of thin wire electrodes 115 a, 119 a formed inparallel arrangement. The thin wire electrode 115 a, 119 a has a widthof about 100 μm, a pitch of about 2 mm and a thickness of about 60 μm. Aset of about 50 thin wire electrodes is formed on a surface of thephotoelectric conversion portion. Such thin wire electrodes 115 a, 119 aare formed, for example, by the steps of screen printing a silver pasteand curing the silver paste at temperatures of a hundred and severaltens degrees. The collector electrode 115, 119 may include a bus barelectrode.

A wiring material 120 is electrically connected to the collectorelectrode 115, 119. The conductive adhesive film 5 is used forconnecting the wiring material 120 to the collector electrode 115, 119.The conductive adhesive film 5 is pressure bonded to place to which thewiring material 120 is bonded. The conductive adhesive film 5 to bepressure bonded has a width equal to or slightly smaller than that ofthe wiring material 120 to connect. If the wiring material 120 has awidth of 0.5 mm to 3 mm, for example, the conductive adhesive film 5also has a width of 0.5 mm to 3 mm in correspondence to the width of thewiring material 120. As shown in FIG. 5, this embodiment employs threelengths of 0.5 mm-wide wiring material 120. As shown in FIG. 4,therefore, three strips of conductive adhesive film 5 having a widthcorresponding to that of the wiring material 120 are pasted on each ofthe front and back sides of the solar cell 1 at places to which thelengths of wiring material 120 are bonded.

The wiring material 120 is pressed against the conductive adhesive film5. The conductive adhesive film is heat treated under pressure forthermally setting an adhesive layer thereof so that the wiring material120 is connected to the collector electrode 115, 119.

The above description is made by way of example where the collectorelectrode 119 on the back side comprises the thin wire electrodes 119 a.In the case of a photovoltaic module arranged not to allow lightincident on the back side, however, the module may also employ a solarcell having a metal electrode formed on the whole surface of the backside thereof.

As shown in FIG. 6, each of the plural solar cells 1 is electricallyconnected to its adjoining solar cell(s) by means of the wiring material120 made of flat copper foil or the like. Specifically, one end of thewiring material 120 is connected to the collector electrode 115 on anupper side of a given solar cell 1 while the other end thereof isconnected to the collector electrode 119 on a lower side of anothersolar cell 1 adjoining the given solar cell 1. These solar cells 1 areconnected in series by means of the wiring material 120 so that thephotovoltaic module 10 may provide a predetermined output of 200 W, forexample, by way of a crossover wiring or lead-out wire.

As shown in FIG. 2, the plural solar cells 1 are electricallyinterconnected by means of the wiring material 120 made of the conductorsuch as copper foil. The solar cells are sealed between a translucentsurface member 41 such as glass or translucent plastic and a backsidemember 42 with a translucent sealing material 43 such as EVA (ethylenevinyl acetate) having excellent weather resistance and moistureresistance. The backside member comprises a member such asweather-resistant film, glass or plastic.

The photovoltaic module 10 is fitted in outer frames 20 made of aluminumor the like by applying a seal material to outer peripheries thereof asneeded. The outer frame 20 is formed of aluminum, stainless steel, rollforming steel sheet or the like. As needed, a terminal box (not shown)is attached to a surface of the backside member 42, for example.

In order to electrically connect the wiring material 120 made of theflat copper foil or the like to the above-described solar cells 1 bymeans of the conductive adhesive film 5, the conductive adhesive film 5is first pasted on the collector electrodes 115, 119 on the front andback sides of the solar cells 1, respectively, as shown in FIG. 4.

The resin adhesive component of the conductive adhesive film 5 is aresin adhesive which primarily consists of an epoxy resin and contains across-linking promoter such that rapid cross-linking is promoted byheating at 180° C. to set the resin adhesive in 15 seconds or so. Thisconductive adhesive film 5 has a thickness of 0.01 to 0.05 mm. The widthof the conductive adhesive film is preferably equal to or slightlysmaller than that of the wiring material 120 in view of the fact thatthe film may shield the incident light. The embodiment employs aconductive adhesive film 5 in the form of a belt-like film sheet havinga width of 0.5 mm and a thickness of 0.02 mm.

As described above, the conductive adhesive film 5 must have a width of1 mm or more to be wound on the feeding reel. In conventional practice,a mechanism employing three feeding reels for feeding three strips ofconductive adhesive film has been adopted. This results in complicatedstructure and cost increase.

Therefore, the embodiment has an arrangement which permits theconductive adhesive film 5 fed by a single feeding reel to be split intothree film strips and delivered simultaneously. In this arrangement, theconductive adhesive film 5 to be delivered has a width equal to orsmaller than that of the wiring material 120 such as to reduce lightshielding by the conductive adhesive film 5. According to theembodiment, the feeding reel 51 having a 1.7 mm-wide conductive adhesivefilm sheet 50 wound thereon is prepared, as shown in FIG. 7 and FIG. 8.The conductive adhesive film sheet has a width more than the total widthof three 0.5 mm-wide strips of conductive adhesive film 5 or a width of1.6 mm to 2.0 mm, for example. The conductive adhesive film 50 unwoundfrom the feeding reel 51 is split into the three 0.5 mm-wide strips ofconductive adhesive film by means of a splitting cutter 54 a and thestrips of conductive adhesive film are pasted on the solar cell 1.

Referring to FIG. 7 and FIG. 8, the following description is made on amethod comprising the steps of preparing the feeding reel 51 having theconductive adhesive film sheet 50 wound thereon, splitting theconductive adhesive film sheet 50 unwound from the feeding reel 51 intothe three 0.5 mm-wide strips of conductive adhesive film, and pastingthe strips of conductive adhesive film on the solar cell 1.

FIG. 7 is a plan view showing the steps of feeding and pasting theconductive adhesive film and FIG. 8 is a side view showing the abovesteps.

As shown in FIG. 7 and FIG. 8, the conductive adhesive film sheet 50 iswound on the feeding reel 51, the film having the width of 1.7 mm, forexample, which is more than the total width of three 0.5 mm-wide stripsof conductive adhesive film. The conductive adhesive film sheet 50 isunwound from this feeding reel 51. Disposed downstream of the feedingreel 51 is a splitting stage 54 which splits the conductive adhesivefilm sheet 50 into a required number of strips.

The splitting stage 54 includes the splitting cutter 54 a for cuttingthe conductive adhesive film sheet 50 into strips of a predeterminedwidth, and pressure roller 54 b for pressing the conductive adhesivefilm sheet 50 against the splitting cutter 54 a. The splitting cutter 54a splits the conductive adhesive film sheet 50 into three 0.5 mm-widestrips of conductive adhesive film 50 a, 50 b, 50 c.

The three 0.5 mm-wide strips of conductive adhesive film 50 a, 50 b, 50c are guided to predetermined positions of the solar cell 1 by means ofguide rollers 56, 57, 58. The conductive adhesive film strips 50 a, 50 con the opposite sides are diverged to the lateral sides (upper and lowersides as seen in the figure) by the guide rollers 56, 57, 58 while thecentral conductive adhesive film strip 50 b is directly advancedforward. The conductive adhesive film strips 50 a, 50 c move the samedistance from the splitting stage 54 to pasting positions on the solarcell 1. However, the central conductive adhesive film strip 50 b isdirectly advanced forward. In as-is condition, therefore, the film strip50 b moves a shorter distance than the other two conductive adhesivefilm strips 50 a, 50 c to travel from the splitting stage 54 to thepasting position on the solar cell 1. In this embodiment, therefore, alength adjustment mechanism 53 is provided somewhere between thesplitting stage 54 and a place of pasting step in order to ensure thatall the conductive adhesive film strips move the same distance to reachthe pasting positions on the solar cell 1. The length adjustmentmechanism 53 employs rollers 53 a, 53 b, 53 c for bendingly guiding theconductive adhesive film strip 50 b so as to increase traveling distanceto the place of pasting step. In this manner, all the conductiveadhesive film strips 50 a, 50 b, 50 c are guided over the same distancewhereby the resin adhesive film can get used up without being wasted.

At the place of pasting step, the conductive adhesive film strips 50 a,50 b, 50 c are guided to predetermined positions on the solar cell 1 bymeans of rollers 59 a, 59 b, 59 c, 60 a, 60 b, 60 c, respectively.Somewhere on the route to the roller 59 a, 59 b, 59 c, the illustrationof which is omitted, the conductive adhesive film sheet 50 is half-cutso that only the adhesive layer thereof is cut to a length in which theconductive adhesive film sheet is pasted on the solar cell 1.

The conductive adhesive film strips 50 a, 50 b, 50 c held betweenrespective pairs of rollers 59 a, 59 b, 59 c, 60 a, 60 b, 60 c arepressed against the collector electrode 115 (119) on the solar cell 1 bymeans of a pressing member 65. Respective adhesive-layer portions of theconductive adhesive film strips 50 a, 50 b, 50 c are separated from basefilm strips and pasted on the solar cell 1. The base film strips 50 a 1,50 b 1, 50 c 1 removed of the adhesive-layer portions are rewound on atake-up reel 52.

The embodiment has the arrangement which permits the conductive adhesivefilm fed by the single feeding reel to be split into three film stripsand delivered simultaneously. The conductive adhesive film strip has thewidth as small as that of the wiring material 120 or so small as not tobe wound on the reel. The three conductive adhesive film strips havingsuch a width can be fed simultaneously.

As shown in FIG. 9, such a feeding mechanism is disposed on each of thefront and back sides of the solar cell 1 such that respective sets ofthree conductive adhesive film strips can be simultaneously pasted onthe front and back sides of the solar cell 1 without turning over thesolar cell 1.

Next, description is made on a method of bonding the wiring material 120to the solar cell 1 having the conductive adhesive film 5 pastedthereon.

As shown in FIG. 10, each of the plural solar cells 1 is electricallyconnected to its adjoining solar cell 1 by means of the wiring material120. Specifically, the wiring material 120 is placed on each strip ofconductive adhesive film 5 pasted on the front and back sides of thesolar cell 1 such that one end of the wiring material 120 is connectedto the collector electrode 115 on the upper side of a given solar cell 1while the other end thereof is connected to the collector electrode 119on the lower side of another solar cell 1 adjoining the given solar cell1. The wiring material 120 is temporarily fixed to place by temporarilypressure bonding the wiring material under low temperature, low pressureconditions. The step of temporarily fixing the wiring material isperformed as follows. A heater block 70 is pressed down on the solarcell 1 placed on a hot plate 71 at a low pressure of about 0.2 MPa, forexample, so as to press each wiring material 120 against the solar cell1. The heater block 70 and hot plate 71 are operated at temperatures ofabout 90° C., for example, so as to provide low-temperature heating forabout 1 second such that the resin adhesive component is not thermallyset while the wiring material 120 is temporarily pressure bonded andfixed to place. The solar cells 1 with the wiring materials 120temporarily fixed thereto are set in array so as to form a string.

In the case where the conductive resin film 5 containing the conductiveparticles 5 a is used, the heater block 70 is used to pressure bond thewiring material 120 to the collector electrode 115 (119) in a mannersuch that the conductive particles 5 a make contact with both thesurface of the collector electrode 115 (119) and the surface of thewiring material 120 thereby establishing electrical connection betweenthe collector electrode 115 (119) and the wiring material 120.

The pressure bonding and heating may be accomplished by an optimummethod properly selected from a method wherein a metal blockincorporating a heater is pressed against the wiring material to applythe predetermined pressure and heat and a method wherein a pressingmember such as pressure pin and hot air are used to apply thepredetermined pressure and heat.

Subsequently, as shown in FIG. 11, the wiring material 120 ispermanently pressure bonded and fixed to place. In this step, a heaterblock 80 is pressed down on the solar cell 1 placed on a hot plate 81 ata high pressure of about 3 MPa, for example, so as to press the wiringmaterial 120 against the solar cell 1, as shown in FIG. 11. Thetemperature of the heater block 80 and hot plate 81 is raised to, forexample, 120° C. or above and 200° C. or below, such thathigh-temperature heating for thermally setting the resin adhesivecomponent is provided thereby permanently pressure bonding and fixingthe wiring material 120 to the solar cell 1. The solar cells 1 areelectrically interconnected and set in array by fixing the wiringmaterials 120 thereto.

The heating temperature is set to 200° C. for example from the viewpointof throughput and the like and the resin adhesive component is thermallyset by 10-second heating thereby electrically and mechanicallyconnecting the collector electrode of the solar cell with the wiringmaterial.

The pressure bonding and heating under high temperature, high pressureconditions may be accomplished by an optimum method properly selectedfrom the method wherein the metal block incorporating the heater ispressed against the wiring material to apply the predetermined pressureand heat and the method wherein the pressing member such as pressure pinand hot air are used to apply the predetermined pressure and heat.

While the above embodiment uses the conductive resin film as the resinfilm, a resin film free from the conductive particles may also be used.In a case where a resin adhesive free from the conductive particles isused, the electrical connection is established by partially placing thesurface of the collector electrode 115 (119) in direct contact with asurface of a wiring material 120. It is preferred in this case that thewiring material 120 comprises a soft conductive film of tin (Sn), solderor the like formed on the surface of the conductor such as copper foiland the conductive film is softer than the collector electrode 115 (119)so as to allow the collector electrode 115 (119) to be partiallyembedded in and connected to the conductive film.

The string of plural solar cells 1 interconnected by means of the wiringmaterial 120 is sandwiched between the translucent sealing material 43such as EVA and laminated between the surface member 41 made of glassand the backside member 42 made of the translucent member such asweather-resistant film, glass or translucent plastic. Next, a laminatoris used to seal the solar cells 1 between the surface member 41 and thebackside member 42 with the sealing sheets 43. Subsequently, thelaminate is placed in a furnace and allowed to cure throughcross-linking reaction at about 150° C. for 10 minutes wherebyadhesiveness between the sealing material 43 and the surface member 41and between the sealing material 43 and the backside member 42 isincreased. Thus is fabricated the photovoltaic module shown in FIG. 1and FIG. 2.

While the above embodiment is described by way of the example where thesolar cells 1 are interconnected by applying three wiring members 120onto the respective solar cells 1, the number of wiring members 120 isnot limited to three. The invention is applicable to any case where twoor more lengths of wiring material 120 are used on the solar cell.

It should be understood that the embodiments disclosed herein are to betaken as examples in every point and are not limited. The scope of thepresent invention is defined not by the above described embodiments butby the appended claims. All changes that fall within means and bounds ofthe claims or equivalence of such means and bounds are intended to beembraced by the claims.

1. A manufacture method for photovoltaic module, in which a wiringmaterial is electrically connected to an electrode of a solar cell byusing a resin adhesive film, comprising the steps of: unwinding theresin adhesive film from a reel on which the resin adhesive film iswound; splitting the unwound resin adhesive film into two or more stripsin correspondence to lengths of wiring material to bond; pasting thestrips of resin adhesive film on the electrode of the solar cell; andplacing the individual lengths of wiring material on the electrode ofthe solar cell having the two or more strips of resin adhesive filmpasted thereon and thermally setting the resin adhesive film by heatingso as to fix together the electrode of the solar cell and the wiringmaterial.
 2. The manufacture method for photovoltaic module according toclaim 1, wherein the splitting step is to split the resin adhesive filminto strips having a width not greater than that of the wiring material.3. The manufacture method for photovoltaic module according to claim 1,wherein the splitting step employs a splitting cutter for splitting theresin adhesive film into strips of a predetermined width and a pressureroller for pressing the resin adhesive film against the splittingcutter, the splitting cutter splitting the resin adhesive film intostrips in correspondence to the lengths of wiring material.
 4. Themanufacture method for photovoltaic module according to claim 1,employing: a first reel on which a resin adhesive film corresponding toan electrode on a front side of the solar cell is wound; and a secondreel on which a resin adhesive film corresponding to an electrode on aback side of the solar cell is wound, and further comprising the stepsof: unwinding the resin adhesive films from the first and second reels,respectively; and splitting each of the unwound resin adhesive filmsinto two or more strips in correspondence to the lengths of wiringmaterial to bond.
 5. The manufacture method for photovoltaic moduleaccording to claim 1, wherein a length adjustment mechanism is providedsomewhere between a place of the splitting step and a place of thepasting step in order to ensure that all the strips of resin adhesivefilm move the same distance from a position of the reel to pastingpositions on the solar cell.
 6. The manufacture method for photovoltaicmodule according to claim 5, wherein the length adjustment mechanismincreases traveling distance by bendingly guiding the resin adhesivefilm by a plurality of rollers on route from the splitting step to thepasting step.
 7. The manufacture method for photovoltaic moduleaccording to claim 5, wherein the splitting step splits the resinadhesive film into three film strips which are separately guided tolateral side routes and a central route by guide rollers and the centralstrip of resin adhesive film is guided to the place of pasting stepthrough the traveling distance increased by the length adjustmentmechanism.
 8. The manufacture method for photovoltaic module accordingto claim 1, wherein the resin adhesive film comprises an adhesive layeroverlaid on a base material and a take-up device for taking up the basematerial is disposed downstream of the pasting positions on the solarcell.